SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1403b0786a53bb1251d8c46aa2fa2bd3e661ef4a6075653a80a7b29fe702112' 
  AND token = 'd4oVxoxJkNzPD/uLeUgMZoMQ/KZCotX/CRTE4vMzR0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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