SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8708d668873c673604a88b48b3e72cc89016d8550cfba042a7fc7efcf76197ef' 
  AND token = 'fdBw4IDG4xJp3GVUFH9Vx9aJstHuUq+2INfC8p3dKsc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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