SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c3f2313086eb339a90464b059ae7aac35f76ca09773c4d0d6343eaf7b69f7345' 
  AND token = 'Pgj7FvdgTfiqussWDYpALn6WuG70Vw7zD1e+FhRYIiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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