SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a781ef91de823106c4f72b0178b78f0142131255d5f8b0e8e35c9555d072bae' 
  AND token = 'x23wADxYpfUOheHmwAHySwEoNQvcn/TiSar+mRAf2JI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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