SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6b227db83b334462e2dfd4410da8b5f935db9f8b9b657f5eba87bd295ff0663' 
  AND token = 'DTrBzLJ+m17ceLVnJcsFRGxGwXfvuzLOEIm6BP09Eac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}