SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d632d1375dc32a7f2e652bb745823c60c508dda49d4ef0d46781d358dc37b39' 
  AND token = '/jVAIJyopPfHqmqL+CFu9BsYGJHIoR42nmN/j5fIlKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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