SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de4daa52c4e8aa3c9fd6c1d9c12eba1c2055daa9726c0bd642c64a38cc309041' 
  AND token = 'kkXNWHBPHhPH9Kl4n4I7lgj1yh1gw2WENOgJW+hoP/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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