SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40337e7f7ad8e995d17775080f75719fefe0a690639c04604341f1191f7994ec' 
  AND token = 'vsSiXEA8FsWOjguXGymhnNnnJTuYR3saKvV9fV46vwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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