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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f42d5cba4c564c9120e6315aea48c9bb849b4e329eed24463821b858f671aeb' 
  AND token = 'YRTLtRyXdZsnm05k9AaHvRdfLE7sPnfvQ+W7S7bgaNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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