SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78550581056aaceab446817b566c1f52f145236ef382e75374741ba0628ffbfd' 
  AND token = 'gwlOrCNhFK+Yw7lyNQzB92kgyhxKrOiBFN2COFkL4QQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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