SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd9eaee3200e6fb6ad3d04611380640f2ae8135618ec0f19fb01256e0c26db24' 
  AND token = '5I6WOQ9SMuAqffwRejQHThqleZg3KnooHETtPVWLIQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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