SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2640c0d83fb7648bad86f6afb677098a7835ec7b9e2fb1016339ff94a4b85af9' 
  AND token = 'CCjTkdDdwteJQ8W4UqMZTrPHgRncUBAZTFNYtFYJ5po=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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