SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8cf7bf7ef58713ecac08c90757981359cf7ff796a55ce665f57b7b414eb5873' 
  AND token = 'p41Uc11ZHMsIsDwXUYzbU8qKYZRJQ0MVBODtSDUgYWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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