SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f2b2b687421ea6b03806bb6e4564647592db5665cc4e58883f3e9801776a967' 
  AND token = 'F1RwaFoQANACfVXCHVz2Cw0K6VkDCUMYeJRCYLwLjkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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