SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16ef357751afad44a475d0aa286877dccb403851b3166c25198948a18e620469' 
  AND token = 'Ijig/GEhUDuPVUhpR/xuV+Vgy9eEcr5NzTdtc0ttnI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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