SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cddc6b36b613187321e61990cdce05ce332ef2e45f6afd56fc018aa935959bd' 
  AND token = 'wQwx7h0hRWJz+3RIv6FVFp703qRv9ZAoiCGBvco478Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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