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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9b8258ff81ca5f16d8fcc4a665554be48ce69d25b60285a5dae98d2fed7e6dd' 
  AND token = 'EVn61hsFNtmgXjcWO+SaQk9kZIG9n8MUZrMMnbXYK9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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