SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'caefe1573847872d16f97f0268b402da9ddebc526f6dd054683638276977217d' 
  AND token = '1GpAoCiCs2jzOPZ5yG/bcbzQiIHr6kmHwhNYImNWQrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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