SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5590bee87cebbe65ca7eb5a49d6ce7ddff31aa44663fa59822399c76c5a58955' 
  AND token = 'JrThgOdbPvF17Zt1ePBsr8kQc18cfVOEotkQLAN9w+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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