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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8748e9f084655b4da1350129235967c0483db182f463b7dc9e0c26375aa066f5' 
  AND token = 'WnA8VqmaWDRA35N8cnxFXqUCIBpE2LLHAwwDvWtiryM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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