SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9790edf21cc0083e85686e19917c76ebdcad16c034e69a9f5357ae0b900a7d90' 
  AND token = 'd+BubO1GTufi7fF9U2lRWe3jllAneigebDbuGs5T1hM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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