SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '642974251ea578a68e5424cbea1c0411994ac58709cb1c103f181c40c278b93b' 
  AND token = 'i+qNXawxkAoDJZJ9gwdXAse4OmqunP4Q0XggrLpwcQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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