SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27c03c753c84969200d60d46da2fa85c6d8ab847384aacf62888baa77949abbc' 
  AND token = 'v/coYQBrQShC9hpZddWsSKS0F28CMAudWDHTSRI5DUA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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