SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b8aa5d8bd0559b1be2382326b1dce3aec44ced367792b9185ee529a9fff7517d' 
  AND token = 'XEv8a8mF5EDX3ZhWD1YI20U5Lif1JhzO+VJ0/Kcd0VQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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