SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0746d141ac801cd212429e9a98c961bf10b85dccb7efc5663fe93d1f37aa4db' 
  AND token = 'LTRHxpMhDsCRtz7EeXBmOdIi1dzhAJBM5vFG39MJlvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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