SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2eb3284e1264351ddd2098530365cb42f8732fefd6687ae7fc7ddba89555c81c' 
  AND token = '4dIcrAKrMIiILBou/nLcy9738/YBRtIRxuVjURSyG1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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