SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bb5b69d3ee01c26181f7c8d7ce5720a4f98998b59a3d653edd676732864af06' 
  AND token = '/w8sOQItTLRczWKBmPQj7VfvDvl5uAZZeLQ/mrsCGV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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