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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25b15ce74f554fa3e91f5781a64e57a9257aa973b8bcaab47f0edd0c7714cc31' 
  AND token = '5zHCkyv0ccVxyFo9mtV01CzrDj9h+L5WxWEXGtf5OhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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