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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e351bddb3ddfc4251cebb78da639e1c4475cbb41e9c54efdf94f174e892b8f28' 
  AND token = '+alpYZhsthdLkyXjrScFa9KP5wz6qyWu08bQ5/7vz0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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