SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6947be968405839199615bf1ea1db85cb331bc988198c74bd7cadff352e2524' 
  AND token = 'cNsmqnb1xUFhXBHWnRWhHT1zE0nCaMxZSReYeKxbFXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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