SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '134242b1ac9196da0d13e1977b807cdad575d158a958e6aa4411208263779a1c' 
  AND token = '5c1vUvjRXrFw8X38nC+b0jpxYMUxEyytktH6SCtWf6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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