SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '849857f9a19634d4943ea33d9046f013fd14694febb588fd24d163897de10857' 
  AND token = 'PurAMOdehh2zWavAvl28aYyo53I5BuzENW1iCSlEb6I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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