SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '38ceb4edb87acb262d60079b9652facf596ed379df6d0c1d9e2b5262e287f368' 
  AND token = 'NvHuJclqSXDJ2havohaT4BAaSQZ7bq7rSv4R+ujJmo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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