SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '685620d1b84748b30f515739f2a19a918fe4d0c9c40431d4a4924d85384d4dc1' 
  AND token = 'JlHQ9mmnuPu+IyTKc9sXO4fnOUoLpcdh8aK0EBfMS2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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