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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b81b84040b7d7e69f965083d1cf543f41ca409f5d91d0e429ac1fa4a721643b' 
  AND token = 'Sa3cqDpL1TQ69PVfBCAdX4ElHaltX/LXW5jQJ3V959I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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