SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98b3baca1232f4c4af389d47b836d6838a82b7a85227a5bd1f259ff2b762fa2f' 
  AND token = '1kEWILLEncmgSUXKsIH5fKcPBuCxaUu00Nw1DtcPkHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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