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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76e416eb3f4a9d2c0b16afbc45327d54f8d74ca7dae3dc8a9fcf2cb7373791b8' 
  AND token = 'CNa5N71o5tkROSXQCJLrQiFfCEgGX52WxiRYNbY5Ht8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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