SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39b500119a9461eb212da7e9f493f83e90732a4ec7a905e1be54b3eb364bdb89' 
  AND token = 'EmHvWdvcNS92UBxc4H3gn3ah1llVogQeV3hNnNGgMJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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