SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5a6b16d1a3bee044b3dd9683759229aaf1acf1ac874e0818d986300ffd87fd33' 
  AND token = 'qiETegm0eVqgM4YeZ/b6/jvy+guLMvKzsLiHm1caTuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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