SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '89ffa626d5fb3f8d7b270a74056a93c84751215d886853681a30496a2d660d51' 
  AND token = 'eQBxERlX1eQYLdSVzFGmt3rJSw2jjlS8MMTp/xTxR6I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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