SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16d35655443bfa20d5729db62d1f4987349f7298b194efd200d0b237b1fce23c' 
  AND token = 't7hJq+JRihy1xIxTu744QDfVG5BdjbFvHOzK3bUcWeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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