SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14915749a871ec45ad9949c415a279ba77f5043f695dfaea688160f7d03e90a5' 
  AND token = 'jIMu6WJubHq5WZGmlF0RqoElSF9WBJiEqnk/2/mjc2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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