SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c12719ccf669165e8fdf299ae4ff3e1132c736390bffe8eb29b1e1fbb19e6260' 
  AND token = 'nAqNaVTZBHsdI4lWyi/nkYfi0tVpcVrtYyd2xueHBCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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