SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '535c1fcedad4eb272a3b8875f59384819bff205d4d3db9734307b766e684f671' 
  AND token = 'vU5l6yxtHgC7v/bBIEw+Tksup5iZIWU/3ypZvxm8Vc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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