SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f0dd877f2eaa415ec17df00cce882cb57f063e885778e3a5ac1f011124c1556' 
  AND token = '5WPL0+uPy7GWdciIKY4LB8b+6qI3wCNlh242XCiKHmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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