SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'bec84d5ebe698bd92a62381b99bb39b87f38d06daf06e9a91353191e4b2db23c' 
  AND token = 'jP9Sy7j5BKue2bv5oi7cya4NawkWvyCBH5zXRv/Lazk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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