SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99e51ad327e838018e9f008b693f61978e5d6ae3fb091f86944308a4c5f6b4d6' 
  AND token = 'xarERZkJZNZPqmgNdydppeLmDuMqVbDHt0hsiqkzAys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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