SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d51c7f7892e297d91026aaf4b5bbaeefc44d1bc9c3eb65ed34308cec59fb6fc' 
  AND token = 'YhqGUjCArlQwWqhmnRzDqvbV9u4mRx8vRIEQmlJPZdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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