SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '210ae2cac4d676467d86651de66e2639f8675185a42ae4477f1bee6ba271312e' 
  AND token = '++GPYnsjlwnyKpNoi+N76qvPLbiFRyAPNRbHG3lVcEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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