SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c920308a3f796927075f3180c7555d6c60aea59da836faf926985b45ecd480df' 
  AND token = 'tSAvjx/0zW7kvXxz8UK4y+JWIggpftjB+Qp0iZq8NFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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