SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a09f93f28a85652f2240ad0aecb84a4a5bff291675c53662f9c6ff19f039f7ad' 
  AND token = 'PrB7Wnu9aqFJAaf6WGP51tBUOsUSFhWexeJJyjW4QSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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