SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6100326a9779fd7366ecf39db954b4ee6f88b0ad837945ea9186fac25dfd7b3' 
  AND token = '6cwvckEE2uhI09vfy7DAEa1yaTnxgVhY/QobRVQNy+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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