SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7df85594b5c108aa6d7f16d54698436e811be2991a0a0089901a39692797178f' 
  AND token = 'UheO3MOljKjA5c90SUYFTyOIZIVOFZGSki3IZLKB35I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}