SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5491c43b2980f804786907381b4ef1b9c8a483db07c34b97fa6be41573d36da0' 
  AND token = '+ge7lCuMB5xGf1DgRBYpTf0P3lmjBkNp9lltAhXWMtQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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