SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9f6d7bdb02a48d1d5a9730fd43026f85b615087e99e204842cce844ce594760a' 
  AND token = '8WHJ6k+ct2nQYUKCpBFN5xLhx+nAw2PGn2w2ku+qDHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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