SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'beaec5d06f05d24d37c2d70c17b517becd0b1718bf2059d60cd8074137b9cc56' 
  AND token = 'gSSaja3ZlaVk1xJRDmLnJAlbXdyw9Mo5XiXODJ+jLPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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