SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dee0aec16a01d299385abffdafcec66a67231ee1eb4d630c300cf6d6de299a4c' 
  AND token = 'USnrC1y4EcSwQDbCXFtAgjZcaBJwji6YtpHgLLf7R7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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