SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a857564ab0811431068decd9afbfca7190a0cf41eb817368a50d9a97fcdb0bca' 
  AND token = 'VhmP6DmTVQ3eZzXmcKV2lu8Q0TDeeiiXPM9s/Lh/R6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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