SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2deb6ec3d6faaeedd99094cb7d48ffad37eff3ccea48305e1724d844b77242b' 
  AND token = 'PC65OAM5T66kPSbI0TBcyOhb9hfi21xnQhMcAkyuAbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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