SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b7be8f205c26867ab08397385853da1182b1e718a1f3d864fb9b9cd56c4928d' 
  AND token = 'UlF5+lhDIhMytKvBgwcqzH8p2dai5r1HhBqe3gucJRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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