SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35d0b9a68211c776babfddd3c98e184e2d23ee95760522f40401855e67dabb4b' 
  AND token = 'JxUorjhbxmPjNVQjRGQ66uLi09O4/XpTJ/zOdPaKHvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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