SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12e02936a449d0180e68827aae82185621a1e447055d618314212253e5408a48' 
  AND token = 'vzRMdYFII2265FlPvbIQW7vJdkJfU/kLr2lsqMxvQPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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