SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f8d1c0bfde7739f7378f756f2ceb14a100d495d872d0dd6ebe5c8fd5ead386f' 
  AND token = 'hSkpvuFu0ckZl6s34W9fqeZBvkqA/8I4h0zL+cJDtt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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