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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76f42992301d97f2c3b8b04edd6cd1a8bbae4ed76f5ff3151d9aae5b14f5e3a3' 
  AND token = '7Bk/0I+srW7KYdStKu95pn3Dv5rbgxQ/EoOm2NbC2wk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}