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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dec73bbb6d9b58efca6237567e9f0577cce0d21e726949e0806f0ea975cb3e87' 
  AND token = 'm7S65IWU1sfV7SRf3Ir+yhMeTLelFSv/uOEGRnESr9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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