SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08dc6b9698f88dcab7175e1f2776e82f50ab015eec46f419b196f2f66867eace' 
  AND token = 'VX3HIin83F3SnckukFdlW3v5/d0A1zHKzGFlsl9mqeU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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