SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '336ae0fdced3e8a35bde62656782d58ae1e65b496bf6a5bb62dd0f32525be26b' 
  AND token = 'LCMgWGdIxJku3SZT2+QRwRDuuBduijERMsIMEzN/+GY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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