SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4945fe7ee939bf6961ebc76a04bf760fc1893efc28b64232cfa78f4203d0be5' 
  AND token = '2jEgDTt2SVSgh41Qn9P8ThMtGWvMV+bvlLd/YkAIlLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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