SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e035e1c32dc40e813600feac65ea8548bb494b39bb8d18a3698388a567e73fb' 
  AND token = 'j8bjjRY3dHpZGlMa8HhSUvN0m+iVEbVXWKBPxKDJBL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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