SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '478758807e166d54e16f57fee421cb8bc092253e9aa31afe44fd7b526ba15333' 
  AND token = '27pRwK8B3gTJIIxMwwH4LpJjfurGjmdQLJHmsJFJvlk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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