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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8e1749e6cb7e0782b5d13a6642534ffc9f63d86252f0a46313a203ea7cb2e71' 
  AND token = 'YwMvNV+q8iQxTfUaUZe81Cpqbq7jMxtebQDwDtcl5hs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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