SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f456dcbecbd1501cb0db0e09e100ae0377e03ac5752deff8113d6df652a77e57' 
  AND token = 'rtKHXsa1Td+UnSAXgWCXoKwnCTbtivge4H/9lhtWo1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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