SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e651005aeeda755de92370e25d86dd813767a3a97bea90b6cbf467736898ac56' 
  AND token = '3CncbCJbXotSgYSXZIQVAvL9onwXOIxSwVd7LVaLEVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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