SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '775dad3cbab38903614f535f86241a1c848b86721ef946e0b4647bf201eb4be8' 
  AND token = 'GdN2RXTgaw5HLeVkAecUwPQq9Uv0FM1AgChM5YYN+TQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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