SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5bc546cbff7ecf1641a2a9a4cd71b68875fba540d9ccf3c8b958baddefdc4b6' 
  AND token = 'yc6amneDqyTvGMdCdc68YfqgH/UeMmYiQPFHzyYKD8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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