SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de51aa67a42bb1f5d5a73a560fbac4280e9d13a866c317c5f754f5d672127e15' 
  AND token = 'Bd+HFbY5dT86GV8tKLcDQOVEeeywBNbxdPkAwR1ehYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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