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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3e534e21546edc3cb6cc64f13a52494e8265da0b6c3bc3d4abb582187add8f9' 
  AND token = 'QFfSeXlgsmu2wupqdkcg8qu+ntqUxPCOPt53/iHKZhQ=' 
  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"
    }
  }
}