SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fbe057dd1bb1b889e91372dbabdd66ad74adbf20da5c195cdebd14308d05212' 
  AND token = '8EH+GDuMbXsmCPZ8wYh7GhkJdI1VGInW3isoUs90Lf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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