SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c399fd36638109f48b3ec4bf4b57794ae3afdc5d90f298793564a69adde04a1' 
  AND token = 'W6zftQmVwW0R/7G9sWEvfpp4wFjalEXgmrOeBF9QqA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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