SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ae2dd08670fa2bae1b0eedc03000434c9859a35ef60d30b42b998a5406f856c' 
  AND token = 'NZgyZ8p+NVw8/jHPMuEM2YtdHOrLOUcZCZXIoaRcPl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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