SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5299089d9fecc90c168a938f349bdcf223b7824a7615fd36b1b10e14d6f8e752' 
  AND token = 'kLBpQm4TmnEql7v6vfpxwQt+mYQisaMWs0EgD8akz84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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