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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '770e7551179ca1ea5e88ee197167674d1da6da00951f1017d854e63674f1701a' 
  AND token = 'MRaIouBGhOHtWM4ORiokWt8XHp+OAVdM7h4Z4UjTrMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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