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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c5e1e9b08a033e0453ed8196707982f849304b50935d635952831e059911a27b' 
  AND token = 'QOOVNgJaZcWIZF3F1T1RX/CwwWyfTbo3c2+KQk51afU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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