SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a320b5982a6bf18e2ab09ffa0ff031ac635ff8a0a4152a4cdd9d88c5a6dce83a' 
  AND token = '7RQYLHdH/jEhJVMnD+s27ij0G10qhuYjnry7WA4+1pU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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