SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '861c5c51f3cd717eb0463606dce6c4530b9867a19d5ae3e1b6af34c5c1b22791' 
  AND token = 'BFZwKkhAH1X3A3DyV5MLzQvRxljS1vKgYAJjFFoCg5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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