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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efdcbadc9257f3f83dc2c7a46e9060f5936248642a6b931d8d53ce1402352461' 
  AND token = 'YyQyccdyxfvOnS2dcotuagDVIHUAxg8gchfUc+uQBCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}