SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e7fa45ad10c6f97d47dfba06e3566816dabb6e4e59ecfb2d6435196682555e5' 
  AND token = 'euSN9LXcQaS6KRRsiGEJFGBwHwQPTRxaX4AUuS4zCeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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