SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c651afc742ca2cd43c3d9f83659476e548a1b92951ff37c2e2a1058b0c09bcc3' 
  AND token = '3KClYM0fpnF/agZYIhXUS8jFB2B0NzoaXHTuG/HSpRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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