SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '312973eb9c905e6cb74ec47d14d2646e810dd99566cb5407e8a88b5737248e3d' 
  AND token = 'ehTQ+BsYS+zGNVvbXJipGnbg/idtiXtZyc0BlG+PYT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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