SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d5d2b8d2f0df8215acb951e3147695b9831c2a714c782a30479ec22ef7a58f2' 
  AND token = 'phkb4oBwaECSnXYl6DDYDCEq7C470DwT4dpO4Lvyjdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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