SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '557265b8e3d766d3cb24757e978058b2068efcb9b8db798812f718c6ff416188' 
  AND token = 'lytYeDya3Xt8rLApCWssrtOPtLJjNbZX88aZaws6c14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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