SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ab7d121f864cd95cc3fcde718a0a4604bb8d70e0498daac0de86a6936684da4' 
  AND token = 'sA1bIhCxwJOdaE5G12T5ThA9GVOnlkDvepLguRItuSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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