SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c5c0375e64ab48f506b3f184f453ff7ceef820f07881fab810c7936b0c39bed2' 
  AND token = 'HlKf0x4ivSD4qEmHPQ5NF/bVcyUvQirYUx1RwH5VgjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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