SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf0373bb41b39b6dcba394a49ce2ca53b3bec1e58237b188621896d47b3ff4c2' 
  AND token = 'ElpUfIginkf3zLQ5KGOFZmE+KjHnVa2EUtjwJf5e2Q4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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