SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b74269d72c155511af17d7837a5909bd4d5b05dccb3cb80f1519a710d6cca8bc' 
  AND token = '62gflZculZnMB4zKVK5biDZEg4/LawWasl67HRGZI+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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