SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4d948c980ba8d24e8515efeb0a39d9c71205dfc20713a0d50aa144b957f5008' 
  AND token = 'kkNusNHH5NKQp5ZNLyD+CsM6kpmmrdAEdSnmvwjotr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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