SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8f96805aba109a5f45afcb94fca033ac55bc7b55d3ee7da4cdbd8096dde0796' 
  AND token = 'WtmpQceLehWzaWICA+tNCxYokbStQe7TYLzoclhA4vM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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