SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50bafd7c8081f6713c832bea6b788297896bd234424ff160b8a5f19483a6479d' 
  AND token = 'guYFg5ZD8vyHjOeOPu8BEIi2cgsXWTqSd+a/rKdLZWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}