SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b15f53ac8f8acd84a9cb27a2be198888232d7101fc887fa750b929739176f943' 
  AND token = 'WJi7lt2nfCVb6RREDXQ8MM8mobTj6dAGsjmCPppktcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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