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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3b33acb761bb55f22f7b0daeab94ef84d091ed4ee33dc8ed66b8ed23892f498' 
  AND token = 'NTqr2lb1A/NWlq1lQ+uRfiQvB/EFRd8XD27P7ARf55c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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