SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8442186a73a6cd00085439084601d79cfe804a75bf0ede1594985be7c7c76dc' 
  AND token = 'K4CnZcIdmia2aBLmscExMOHVpCwxkxiwal27elvuB4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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