SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c47b5c0503636b7f2fd25eede7b6e862c0a96e2a200192b8f5034f08ee0ba1f2' 
  AND token = 'DKNaI9pW9UbP0HXd11uLGyfudMAw2WK0sdwZHQ3NmYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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