SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6332496f6266b8ab11f8598cae44452b7ac506a6c2da81785625b0c5f9bdf7a' 
  AND token = 'O7IYYVWJqOXHtxOgz3VyTsSkeAuKUtg8yyTXLEUjMS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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