SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7bcdb2895f43d58617a65acdc9e5137a4212bf73bdee224dc455c40ca6432a7' 
  AND token = 'ySC/OqDY+BM4+wwTsWQFsGF8z3pMBv9gXk8hZjrbjTE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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