SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c21e580d4dd18bf8c49cca9cbf8eb1d2990305c303d64172954ab368d5bc4573' 
  AND token = 'SLFBKT8Vfx97WkoN9QUO/Ar7jyIiegeEiRo33fbfIBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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