SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85559856bb41a34dd285297a658fe883c31620428c68ba55890f6329431d8dad' 
  AND token = 'GRwMzD1re+6ixDjoM9LYY+aE9MGVh2VVGpVxStJc9i4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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