SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c71f1dc8293f80bc3a4503457b6fee820db1075977a89424229e6ee6f3308b59' 
  AND token = 'TKZpYk3Ouma1JNc8lsIZuTNFZnHhN9ThXh+wcBEePVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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