SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52e544cad7da766839dbfe9d16c5b9fb87c8350af14efc97104e84e9818edb30' 
  AND token = 'E/72tRwtdGrFADKn7EVACpXgPhTV0GJAMWLLVaJlPyU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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